i have a young lilac tree in a middle of a flower border (1 or 2 years old),
we're planning to do raised borders, could i leave the lilac in place without lifting it up and replanting it, or would it damage it if the root ball is buried too deep?

Because of the advice from Goy members (it wasnt doing much), I moved my Lilac to a spot where I didnt mind it having room. It is much happier since the late summer 09 move. About 2 years old, I was surprised how easy it was to move and lots of lovely new growth this year.